Productivity: Mute tweets without urls in Tweetbot

I spent far to much time on Twitter lately. Time wasted that should be
used for building stuff. On the other hand I do not
want to complettely abandon Twitter, because it's a great source of
new links for me.

So I decided to filter out all Tweets without URL's.

I remembered that it was possible using negative lookahead - but frankly
I never used it. I found the answer on stackoverflow.